How do I modify a specific component within a active internalframe?

Hello everybody,

I am still learning java at this point, but I seem to have surpassed the 3 java books I own.

I have an issue here that I am confident that most of you can answer.

I am attempting to change the icon of a button in a internalframe when pressed. The code below shows the text of a button changing (but only the last iframe is being changed, not the active iframe). By answering this question I will understand how to interact with internal frames.
Here is a stripped down version of the code: